1. Field of the Invention
The present invention relates to apparatus for the measurement of ultrafast electrical signals, and more particularly to a measurement probe for making electrical contact for ultrafast signal measurements on, for example, an integrated circuit or device.
2. DESCRIPTION OF THE PRIOR ART
The detection of voltages at points on an integrated circuit by a probe-type measurement device is known in the art.
In U.S. Pat. No. 4,065,717, issued Dec. 27, 1977 to Kattner et al entitled Multi-point Microprobe for Testing Integrated Circuits, a multi-point probe for contacting closely spaced pads of a semiconductor device, having a flexible sheet-like member which carries the probes that make contact with the semiconductor device is described. Japanese Patent No. JA60-73366, issued Apr. 25, 1985 to Gotou entitled Apparatus for Supplying and Measuring Wiring Voltage, describes a system which makes it possible to measure the internal wiring voltages of an integrated circuit mounting printed board and to apply voltage to the internal wiring thereof by laser beam, by providing a photoconductive member and a transparent electrode to the surface wiring region of the mounting printed board. The position of internal wiring to be inspected is indicated by a focusing deflector to which X-Y position data is inputted. The focusing deflector is irradiated with a beam from a beam source and an indicated internal wiring location is irradiated with the focused deflected beam. Indicated internal wiring is irradiated with the beam through a transparent electrode and a photoconductive film. The photoconductive film comes to an equilibrium state only where the beam passes and the transparent electrode and the indicated internal wiring are brought to an equilibrium state. Then, voltage applied to the internal wiring is outputted as digital information from an A/D converter through the transparent electrode and the voltage of the internal wiring can be measured.
U.S. Pat. No. 3,405,361, issued Oct. 8, 1968 to Kattner et al entitled Fluid Actuable Multi-point Microprobe for Semiconductors, describes a system having a multi-point probe for contacting closely spaced pads of a semiconductor device having a flexible sheet-like member which carries the probes that make contact with the semiconductor device. The flexible sheet-like member forms part of a chamber, into which a fluid is introduced to deform said member to cause the probes thereon to make contact with the semiconductor device.
Other references are available which describe the measurement of high-speed pulses.
In U.S. Pat. No. 4,446,425, issued May 1, 1984 to Valdmanis et al entitled Measurement of Electrical Signals with Picosecond Resolution, electrical signals are measured (analyzed and displayed) with picosecond resolution by the electro-optic sampling of the signal being analyzed in a traveling wave Pockels cell. Sampling pulses, from an optical pulse generator such as a colliding pulse mode-locked laser, of subpicosecond duration are transmitted through the cell as polarized light and translated into a difference output corresponding to the difference in amplitude between the transmitted and rejected components of the polarized light. The signals, synchronous with the optical sampling pulses, are generated to propagate along the cell in a direction transverse to the transmission of the optical sampling pulses and in variably delayed relationship therewith. A separate beam of the optical pulses is chopped and used to activate a photoconductive device which produces the signals. The difference output is processed, preferably by a lock-in amplifier and signal averager; the lock-in amplifier is synchronized with the chopping of the launched pulses, and displayed on a time base synchronous with the variable delay of the pulses. Accordingly, the signal is displayed on an expanded time scale for measurement and other analysis. The response of photodetectors, photoconductive switches and other ultrafast light activated devices can be determined, when these devices are used as the source of the signals being analyzed and displayed.
In U.S. Pat. No. 4,218,618, issued Aug. 19, 1980 to Mourou entitled Apparatus for Switching High Voltage Pulses with Picosecond Accuracy, switching of high voltage pulses of durations from about 10 microseconds to 10 milliseconds with picosecond accuracy is accomplished by a laser activated semiconductor switch made up of a body of high resistivity semiconductor material, such as nearly intrinsic silicon, integrated into a wide band geometry, which is part of a transmission line. The high bias voltage pulses are obtained by charging the line in synchronism with the generation of the laser pulse. The high voltage bias pulse width and the length of the body is selected so as to prevent thermal breakdown of the semiconductor with such pulse widths. The energy of the laser pulse switches the high voltage to produce a multikilovolt output pulse suitable for driving devices, such as streak cameras or Pockels cells, by the same laser, which need to be synchronized with picosecond accuracy to the laser pulse. The length of the transmission line may be varied to adjust the width of the multikilovolt output pulse.